Ink jet recording method and apparatus therefor

ABSTRACT

PCT No. PCT/JP95/00717 Sec. 371 Date Nov. 26, 1997 Sec. 102(e) Date Nov. 26, 1997 PCT Filed Apr. 12, 1995 PCT Pub. No. WO95/27620 PCT Pub. Date Oct. 19, 1995An ink jet recording method which can inhibit feathering or bleeding in a print and provide a sharp color image is disclosed. The ink jet recording method according to the present invention comprises the steps of: ejecting a droplet of an ink composition, comprising a colorant, a thermoplastic resin, and water, onto a recording medium to deposit the ink droplet on the recording medium, and heating the recording medium with the ink droplet deposited thereon at the softening temperature of the thermoplastic resin or higher temperature so as to effectively inhibit feathering or bleeding of the ink.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an ink jet recording method and moreparticularly to a "color" ink jet recording method.

2. Background Art

Ink jet recording methods should generally satisfy the followingrequirements.

1) Realization of a high-quality image free from feathering or bleeding.

2) Rapid drying and fixation of ink composition.

3) High print density.

4) Stable ejection of an ink composition through a nozzle and an inkpassage without clogging.

5) High storage stability and safety of an ink composition.

In particular, printing without feathering is more important in colorimage printing than in monochrome color printing. In the color printing,a plurality of color ink compositions are printed on an identicalrecording medium. In order to provide a color print free from an unevencolor, the boundary of the colors should be clear. Thus, the spread andmixing of ink compositions at the boundary region thereof should beprevented.

The use of an ink composition having a high viscosity may be effectivefor preventing feathering or bleeding. The ejection and feeding of suchan ink composition having a high viscosity, however, may require highenergy, resulting in unsatisfactory efficiency.

Various proposals have been made in order to realize printing free fromfeathering or bleeding. For example, Japanese Patent Laid-OpenPublication No.288042/1987 discloses a method in which printing iscarried out with heating a recording medium. This publication, however,does not disclose any ink composition containing a thermoplastic resin.

SUMMARY OF THE INVENTION

We have now found that feathering or bleeding of a print can besatisfactorily prevented by depositing an ink composition containing athermoplastic resin on a recording medium by ink jet recording and thenheating the recording medium at a particular temperature or above.

Accordingly, an object of the present invention is to provide an ink jetrecording method which can prevent feathering or bleeding of a print.

Another object of the present invention is to provide an ink jetrecording method which can develop a sharp color in addition to theprevention of feathering or bleeding.

A further object of the present invention is to provide an ink jetrecording apparatus for carrying out the ink jet recording method of thepresent invention.

According to one aspect of the present invention, there is provided anink jet recording method comprising the steps of:

ejecting a droplet of an ink composition comprising a colorant, athermoplastic resin, and water, onto a recording medium to deposit theink droplet on the recording medium, and

heating the recording medium with the ink droplet deposited thereon atthe softening temperature of the thermoplastic resin or above so as toeffectively inhibit feathering or bleeding of the ink.

According to another aspect of the present invention, there is providean ink jet recording apparatus comprising:

a recording means for ejecting a droplet of an ink compositioncomprising water, a thermoplastic resin, a colorant, and a water-solubleorganic solvent, onto a recording medium to deposit the ink compositiononto the recording medium;

a heating means for heating the recording medium, with the ink dropletdeposited thereon, to the softening point of the thermoplastic resin orabove; and

a carrying means for carrying the recording medium to the recordingmeans and the heating means.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing an increase in viscosity of an ink compositionon a recording medium, wherein curve (A) represents a change inviscosity of an ink composition containing a thermoplastic resin andcurve (B) represents a change in viscosity of an ink composition notcontaining a thermoplastic resin;

FIG. 2 is a diagram showing the relationship between the size of an inkdot and the pitch of dots, wherein FIG. 2 (A) represents an ideal sizeof ink dots and FIG. 2 (B) represents a size of ink dots with a positionerror being taken into consideration;

FIG. 3 is a diagram showing the relationship between an ink dot circlein an actual ink dot and ink feathering L;

FIG. 4 is a diagram showing the state of an ink dot formed by the inkjet recording method according to the present invention, wherein FIG. 4(A)is a cross-sectional view of an ink dot on a recording medium formedby the method according to the present invention, FIG. 4 (B) is a planview of ink dots, adjacent to each other, formed by the ink jetrecording method according to the present invention and FIG. 4 (C) is aplan view of ink dots, adjacent to each other, which have beenunfavorably deformed;

FIG. 5 is a diagram showing color mixing in a color print formed by theink jet recording method according to the present invention;

FIG. 6 is a diagram showing color mixing in a color print formed bypenetration of ink compositions into a recording medium;

FIG. 7 is a schematic view of the ink jet recording apparatus accordingto the present invention;

FIG. 8 is a schematic view of an ink jet recording apparatus accordingto the present invention wherein a plurality of printing heads areprovided;

FIG. 9 is a schematic view of an ink jet recording apparatus accordingto the present invention wherein a plurality of printing heads and aplurality of heating means are provided; and

FIG. 10 is a schematic view of an ink jet recording apparatus wherein arecording medium is heated in a non-contact manner, wherein FIG. 10 (A)shows an embodiment wherein a recording medium is heated after printingof an ink composition and FIG. 10 (B) shows an embodiment whereinheating is carried out before an ink composition is printed.

DETAILED DESCRIPTION OF THE INVENTION

Ink Jet Recording Method

The ink jet recording method according to the present invention using anink composition which is described in detail below will now bedescribed.

A droplet of an ink composition is projected to form an ink image on arecording medium. The formation and ejection of the ink droplet may becarried out by means of an ink jet printing head commonly used in theart. The recording medium may be plain paper including acidic paper andneutralized paper.

According to the method of the present invention, the recording mediumwith an ink deposited thereon is then heated. Heating is carried out atthe softening temperature of the thermoplastic resin or highertemperature. Heating causes the viscosity of the ink composition on therecording medium to be initially lowered. Subsequent evaporation of thesolvent results in increased solute concentration and increasedviscosity of the ink composition. Finally, the ink is brought to a filmwhich is adhered onto the recording medium. In the method of the presentinvention, an increase in viscosity can be rapidly attained by virtue ofinteraction among thermoplastic resin particles present in the inkcomposition used. Heating of the ink droplet immediately afterdeposition thereof on a recording medium results in increased viscosityof the ink droplet. Consequently, an ink dot is formed beforeunnecessary penetration of the ink into the recording medium, i.e.,feathering, occurs. Thus, the feathering of an ink on a recording mediumcan be effectively prevented.

While the softening temperature of the thermoplastic resin or abovevaries depending upon the thermoplastic resin used, it is generally inthe range of from 50 to 120° C., still preferably in the range of from65 to 90° C. Heating may be initiated after the deposition of an inkdroplet. Alternatively, an ink droplet may be deposited on a previouslyheated recording medium.

FIG. 1 is a typical diagram showing a change in viscosity of an inkcomposition on a recording medium upon heating according to the methodof the present invention. Curve A represents an increase in viscosity ofan ink composition according to the method of the present invention. Ascan be seen from curve A, an increase in viscosity can be attained in ashort time. On the other hand, curve B represents an increase inviscosity of an ink composition when printing has been carried out inthe same manner as the method of the present invention, except that anink composition which does not contain a thermoplastic resin was used.As can be seen from curve B, an ink composition without a thermoplasticresin exhibits no rapid increase in viscosity.

In the method of the present invention, the ink composition ejectedthrough a nozzle may have a low viscosity. Therefore, printing may becarried out under conventional ink jet recording conditions.

According to a preferred embodiment of the present invention, heating ispreferably carried out so as to bring the viscosity of the inkcomposition to about 1 to 10 Pa.sec or more. According to a preferredembodiment of the present invention, this viscosity value can beattained in a short period of time of about 100 μsec by heating at thesoftening temperature of the thermoplastic resin or a highertemperature.

That the present invention can prevent ink feathering will be furtherdescribed.

FIG. 2 shows ink dots formed on a recording medium. The size of ink dotsin a certain resolution is ideally such that, as shown in FIG. 2 (A),ink dot 1a and ink dot 2a are adjacent to each other. Specifically, theradius of the ink dot is ideally 1/2 of a diagonal line of square 3formed by connecting the centers of adjacent four dots so as for thecenters of the dots to constitute respective apexes of the resultantsquare. In other words, the radius of an ink dot is ideally a valueobtained by the equation: dot pitch x (√2/2).

More specifically, when the resolution is 600 dpi, the dot pitch is1/600 in., i.e., about 42 μm, and a value obtained by multiplying thisvalue by (√2/2), i.e., about 30 μm, is an ideal ink dot radius with theink dot diameter being about 60 μm.

However, in printing of ink dots, a position error often occurs, forexample, attributable to a paper feed accuracy. In order to provide agood image despite the position error, it is common practice to form adot having a radius of about 100 to 150% larger than the ideal size and,according to a preferred embodiment, a radius of about 100 to 120% ofthe ideal size. As shown in FIG. 1 (B), ink dots are formed in such asize that dot 1b overlaps with dot 2b.

In this case, if the ink composition is further spread in only a certaindirection from the ink dot radius thus determined, such a spread isfeathering. In this disclosure, the "ink feathering" is a distance of anink portion extended from an ink dot circle having a radius of dot pitchx (√2/2)×100 to 150%.

"Ink feathering" will be defined more specifically with reference toFIG. 3. Ink 31 deposited on a recording medium is penetrated in a gapbetween fibers 32 of the recording medium to form an ink dot. In somecases, this ink dot is not in a complete circular form. A largest circle33 inscribed with edges of the dot can be drawn. This circle can beregarded as an ink dot circle, and a distance L is created which is adistance between the ink dot circle and the ink portion 34 most distantfrom the ink dot circle. This L is causative of feathering. In thepresent invention, the L is called "ink feathering." According to themethod of the present invention, the recording medium is heated so as tominimize the distance L.

According to a preferred embodiment of the present invention, therecording medium with an ink droplet deposited thereon is preferablyheated so that the "ink feathering" is not more than about 10% of theradius of an ink dot circle having a size of dot pitch x (√2/2)×100 to150%. Still preferably, heating is carried out so that the inkfeathering is not more than about 7% of that.

According to a preferred embodiment of the present invention, therecording medium is heated so that, in an image having a high resolutionof not less than 600 dpi, the "ink feathering" is not more than 5 μm.Studies conducted by the present inventors have revealed that when theink feathering L is brought to not more than 5 μm, dots can be clearlydistinguished from one another with the naked eye even in such a highresolution, giving a recognition of a good image quality.

Further, according to the method of the present invention, the ink dotis deposited as a film on a recording medium. This is shown in FIG. 4(A). An ink dot 42 in a film form is formed on a recording medium 41. Inthe recording method of the present invention, a colorant stays on thesurface of the recording medium, advantageously resulting in an improvedprinting density.

The method according to the present invention can be advantageously usedin the formation of a color image by ejecting ink droplet so as tooverlap with each other or to be adjacent to each other. A first inkimage is formed on a recording medium and then heated in the step ofheating to increase the viscosity of the ink image. After the viscosityis increased to such an extent that new printing on the print causes nobleeding, next printing is carried out. That is, second printing iscarried out at a position on or adjacent to the print, using an inkcomposition which is the same or different from that used for theformation of the first print. The ink composition for the second printbasically comprises the same composition as utilized in the formation ofthe first ink image, i.e., comprises a thermoplastic resin, a colorant,and water. The recording medium with a second print formed thereon isheated so as to inhibit ink feathering. This heating may be also carriedout in the same manner as used in the first heating, i.e., at thesoftening temperature of the thermoplastic resin in the ink compositionor a higher temperature.

As a result, for example, regarding adjacent ink dots, as shown in FIG.4 (B), recording can be carried out so that ink dot 43 and ink dot 44adjacent to ink dot 43 are not deformed. Further, the flow of the inkcompositions into each other does not occur, advantageously resulting ingood color development. On the other hand, deformation of both adjacentink dots brings the ink dots to a shape 45 as shown in FIG. 4 (C),rendering the image unsharp. This is disadvantageous in the reproductionof an image with a high accuracy.

According to a preferred embodiment of the present invention, a goodprint with dots formed adjacent to each other as shown in FIG. 4 (B) canbe formed by simply printing dots at a minimum time interval of 69 μsec.Furthermore, when dots are printed so as to overlap with each other, animage free from bleeding can be provided by simply printing the dots ata minimum time interval of 4 μsec.

Further, it should be noted that the formation of an ink dot in a filmform according to the method of the present invention enables thereproduction of a vivid color. The ink dot film is basically formed of a"transparent" resin and a colorant dispersed in the transparent layer.Thus, the color of the colorant exhibits more vividly in the colorreproduction.

This good color ink reproduction is more advantageous in multi-colorprinting. FIG. 5 is a diagram showing multi-color printing according tothe method of the present invention. In the drawing, a yellow ink printregion 52 and a cyan ink print region 53 are formed on a recordingmedium 51. A region 54 where the two regions overlap with each otherconstitutes a color mixture region. Light emitted from light source 55enters each region and reflects on the surface of recording medium 51 orpasses through each region to reach a viewer 56. Good color developmentcan be attained by a subtractive color process using yellow region 52and cyan region 53. Further, in color mixture region 54, vivid green canbe developed from yellow and cyan by a subtractive color process. On theother hand, in an embodiment wherein an ink composition is penetratedinto a recording medium, a print region as shown in FIG. 6, for example,is formed. Specifically, yellow ink print region 62, cyan ink printregion 63, and region 64 formed of a mixture of two colors are formed.In this case, light from light source 55 reflects on the surface of eachregion to reach viewer 56. Subtraction color by light, in most cases,occurs on the surface of each region. The color development is expectedto be inferior to that in the method according to the present invention.

Third printing may be carried out so as to overlap with or adjacent tothe second print. The ink composition used in this case is alsopreferably identical to the ink composition of the first and secondprints.

Ink Composition

The ink composition used in the ink jet recording method according tothe present invention basically comprises a colorant, a thermoplasticresin, and water.

The term "thermoplastic resin" used herein refers to a thermoplasticresin having a softening or hot-melting temperature of 50 to 150° C.,preferably 60 to 100° C. The term "softening or hot-melting temperature"used herein refers to the lowest temperature among the glass transitionpoint, the melting point, the temperature for bringing the coefficientof viscosity to 10¹¹ to 10¹² P, and the pour point of the thermoplasticresin.

In the heating step of the method of the present invention, a recordingmedium is heated at the softening temperature of the thermoplastic resinor a high temperature. The softening temperature of the thermoplasticresin refers to the lowest temperature among the the softening point,the glass transition temperature (Tg), the melting point, and, in thecase of an emulsion form, the lowest possible film forming temperature(MFT).

The amount of the thermoplastic resin added is preferably about 5 to 40%by weight, still preferably about 5 to 25% by weight based on the wholeink.

Preferably, the resin, when dried under an environment of roomtemperature, does not form a film but a solid or a fragile solid matterand, when heated at the softening or melting temperature or above andthen cooled, forms a strong water-resistant film.

Specific examples of water-insoluble thermoplastic resins include, butnot limited to, polyacrylic acid, polymethacrylic acid, polymethacrylicester, polyethyl acrylic acid, styrene/butadiene copolymer, butadienecopolymer, acrylonitrile/butadiene copolymer, chloroprene copolymer,crosslinked acrylic resin, crosslinked styrene resin, fluororesin,vinylidene fluoride, benzoguanamine resin, phenolic resin, polyolefinresin, cellulose, styrene/acrylic acid copolymer, styrene/methacrylicacid copolymer, polystyrene, styrene/acrylamide copolymer, n-isobutylacrylate, acrylonitrile, vinyl acetate, acrylamide, silicone resin,polyvinyl acetal, polyamide, rosin resin, polyethylene, polycarbonate,polyvinylidene chloride resin, cellulosic resin, epoxy resin, vinylacetate resin, ethylene/vinyl acetate copolymer, vinylacetate/(meth)acrylate copolymer, vinyl chloride resin, polyurethane,and rosin ester.

Specific examples of low-molecular weight thermoplastic resins includepolyethylene wax, montan wax, alcohol wax, synthetic oxidized wax,α-olefin/maleic anhydride copolymer, animal and vegetable waxes, such ascarnauba wax, lanoline, paraffin wax, and microcrystalline wax.

Preferably, the water-insoluble resin is added to the ink composition insuch a form that the resin alone is dispersed as fine particles in anink, that is, in the form of such a resin emulsion form that the resinis stably dispersed in water. The resin emulsion means the emulsion inwhich water constitutes a continuous phase and the resin componentconstitutes a dispersed phase.

The diameter of particles of the resin component is not particularlylimited so far as the particles can form an emulsion. It, however, ispreferably not more than about 300 nm, still preferably about 50 to 200nm.

The resin emulsion can be prepared by mixing resin particles optionallytogether with a surfactant into water. For example, an acrylic resin orstyrene/(meth)acrylate resin emulsion can be prepared by mixing either a(meth)acrylic ester or styrene, a (meth)acrylic ester and optionally(meth)acrylic acid and a surfactant into water. The surfactant is notparticularly limited, and preferred examples thereof include anionicsurfactants. They may be used alone or as a mixture of two or more.

Known resin emulsions may be used as such a resin emulsion. Forexmaples, resin emulsions such as described in Japanese Patentpublication No. 1426/1987 and Japanese patent Laid-Open Nos. 56573/1991,79678/1991, 160068/1991, and 18462/1992 as such may be used.

Further, it is also possible to use commercially available resinemulsions, and exmaples thereof include Microgel E-1002 and E-5002(styrene/(meth)acrylate resin emulsion, manufactured by Nippon PaintCo., Ltd.), Voncoat 4001 (acrylic resin emulsion, manufactured byDainippon Ink and Chemicals, Inc.), Voncoat 5454 (styrene/(meth)acrylateresin emulsion, manufactured by Dainippon Ink and Chemicals, Inc.), SAE1014 (styrene/(meth)acrylate resin emulsion, manufactured by Nippon ZeonCo., Ltd.), and Saivinol SK-200 (acrylic resin emulsion, manufactured bySaiden Chemical Industry Co., Ltd.).

In the ink composition used in the present invention, a water-solublethermoplastic resin may be used. Preferred examples of the water-solublethermoplastic resin include polyethylene oxide, glue, gelatin, casein,albumin, gum arabic, alginic acid, methyl cellulose, carboxymethylcellulose, hydroxyethyl cellulose, and polyvinyl ether.

Pigments, water-soluble dyes, disperse dyes, water-insoluble dyes (inthe case of addition by kneading with a resin emulsion) are usable asthe colorant. Any of the above colorants may be used so far as they havegood affinity for water as a main solvent or can be homogeneouslydispersed when used in combination with a dispersant or the like.

Pigments usable in the present invention include organic pigments andinorganic pigments. Examples of the pigment for black include carbonblacks (C.I. Pigment Black 7), such as furnace black, lamp black,acetylene black, channel black; metals, such as copper, iron (C.I.Pigment Black 11), or titanium dioxide; and organic pigments such asaniline black (C.I. Pigment Black 1).

Examples of the pigment for color include:

C.I. Pigment Yellow 1 (Fast Yellow G), 3 and 12 (Disazo Yellow AAA), 13,14, 17, 24, 34, 35, 37, and 42 (yellow iron oxide), 53, 55, 81, and 83(Disazo Yellow HR), 95, 97, 98, 100, 101, 104, 108, 109, 110, 117, 120,138, and 153;

C.I. Pigment Orange 5, 13, 16, 17, 36, 43, and 51;

C.I. Pigment Red 1, 2, 3, 5, 17, and 22 (Brilliant Fast Scarlet), 23,31, 38, and 48:2 (Permanent Red 2B (Ba) ), 48:2 (Permanent Red 2B (Ca)), 48:3 (Permanent Red 2B (Sr) ), 48:4 (Permanent Red 2B (Mn) ), 49:1,52:2, 53:1, and 57:1 (Brilliant Carmine 6B), 60:1, 63:1, 63:2, 64:1, and81 (Rhodamine 6G Lake), 83, 88, and 101 (Red Iron Oxide), 104, 105, 106,and 108 (Cadmium Red), 112, 114, and 122 (Quinacridone Magenta), 123,146, 149, 166, 168, 170, 172, 177, 178, 179, 185, 190, 193, 209, and219;

C.I. Pigment Violet 1 (Rhodamine Lake), 3, 5:1, 16, and 19 (QuinacridoneRed), 23 and 38;

C.I. Pigment Blue 1, 2, and 15 (Phthalocyanine Blue R), 15:1, 15:2, and15:3 (Phthalocyanine Blue G) , 15:4 and 15:6 (Phthalocyanine Blue E),16, 17:1, 56, 60, and 63;

C.I. Pigment green 1, 4, 7, 8, 10, 17, 18, and 36; and processedpigments, such as graft carbon prepared by treating the surface ofpigments with a resin or the like.

The water-insoluble colorants may be, if necessary, used as a colorantdispersion prepared by dispersing the colorant using a dispersant.

Water-insoluble dyed usable in the ink of the present invention includedirect dyes, acid dyes, base dyes, and food dyes, and examples thereofinclude, but not limited to:

C.I. Direct Black 9, 17, 19, 22, 32, 51, 56, 62, 69, 77, 80, 91, 94, 97,108, 112, 113, 114, 117, 118, 121, 122, 125, 132, 146, 154, 166, 168,173, and 199;

C.I. Direct Red 2, 4, 9, 23, 26, 31, 39, 62, 63, 72, 75, 76, 79, 80, 81,83, 84, 89, 92, 95, 111, 173, 184, 207, 211, 212, 214, 218, 221, 223,224, 225, 226, 227, 232, 233, 240, 241, 242, 243, and 247;

C.I. Direct Violet 7, 9, 47, 48, 51, 66, 90, 93, 94, 95, 98, 100, and101;

C.I. Direct Yellow 8, 9, 11, 12, 27, 28, 29, 33, 35, 39, 41, 44, 50, 53,58, 59, 68, 86, 87, 93, 95, 96, 98, 100, 106, 108, 109, 110, 130, 132,142, 144, 161, and 163;

C.I. Direct Blue 1, 10, 15, 22, 25, 55, 67, 68, 71, 76, 77, 78, 80, 84,86, 87, 90, 98, 106, 108, 109, 151, 156, 158, 159, 160, 168, 189, 192,193, 194, 199, 200, 201, 202, 203, 207, 211, 213, 214, 218, 225, 229,236, 237, 244, 248, 249, 251, 252, 264, 270, 280, 288, 289, and 291;

C.I. Acid Black 7, 24, 29, 48, 52:1, and 172;

C.I. Acid Red 35, 42, 52, 57, 62, 80, 82, 111, 114, 118, 119, 127, 128,131, 143, 151, 154, 158, 249, 254, 257, 261, 263, 266, 289, 299, 301,305, 336, 337, 261, 396, and 397;

C.I. Acid Violet 5, 34, 43, 47, 48, 90, 103, and 126;

C.I. Acid Yellow 17, 19, 23, 25, 39, 40, 42, 44, 49, 50, 61, 64, 76, 79,110, 127, 135, 143, 151, 159, 169, 174, 190, 195, 196, 197, 199, 218,219, 222, and 227;

C.I. Acid Blue 9, 25, 40, 41, 62, 72, 76, 78, 80, 82, 92, 106, 112, 113,120, 127:1, 129, 138, 143, 175, 181, 205, 207, 220, 221, 230, 232, 247,258, 260, 264, 271, 277, 278, 279, 280, 288, 290, and 326;

C.I. Basic Black 8;

C.I. Basic Red 12, 13, 14, 15, 18, 22, 23, 24, 25, 27, 29, 35, 36, 38,39, 45, and 46;

C.I. Basic Violet 1, 2, 3, 7, 10, 15, 16, 20, 21, 25, 27, 28, 35, 37,39, 40, and 48;

C.I. Basic Yellow 1, 2, 4, 11, 13, 14, 15, 19, 21, 23, 24, 25, 28, 29,32, 36, 39, and 40;

C.I. Basic Blue 1, 3, 5, 7, 9, 22, 26, 41, 45, 46, 47, 54, 57, 60, 62,65, 66, 69, and 71;

C.I. Disperse Yellow 3, 5, 56, 60, 64, and 160;

C.I. Disperse Red 4, 5, 60, 72, 73, and 91;

C.I. Disperse Blue 3, 7, 56, 60, 79, and 198;

C.I. Disperse Orange 13 and 30; and

C.I. Food Black.

Water-insoluble dyes used in a dispersed state or in the form of amixture thereof or a solution thereof in the resin include, but notlimited to:

C.I. Solvent Black 3, 5, and 22;

C.I. Solvent Yellow 19, 44, 98, 104, 105, 112, 113, and 114;

C.I. Solvent Red 8, 24, 71, 109, 152, 155, 176, 177, and 179;

C.I. Solvent Blue 2, 11, 25, 78, 94, and 95;

C.I. Solvent Green 26;

C.I. Solvent Orange 5, 40, 45, 72, 63, 68, and 78; and

C.I. Solvent Violet 13, 31, 32, and 33.

The amount of the dye added may be determined depending upon the kind ofthe dye, the kind of the solvent component, the properties required ofthe ink and the like. It is preferably about 0.2 to 10% by weight, stillpreferably about 0.5 to 5% by weight.

The ink composition used in the present invention may contain an organicsolvent in addition to water. Specific preferred examples of the organicsolvent include high-volatile monohydric alcohols such as ethanol,propanol, isopropanol, and butanol. It is also possible to use ahydrophilic, high-boiling, low-volatile organic solvent from theviewpoints of preventing nozzle clogging and improving the moistureretention of the ink composition. Specific preferred examples of thehydrophilic, high-boiling, low volatile organic solvent includepolyhydric alcohols, such as glycerin, ethylene glycol, diethyleneglycol, triethylene glycol, propylene glycol, dipropylene glycol,hexylene glycol, polyethylene glycol, and polypropylene glycol, andmonoetherified, dietherified, and esterified products thereof, forexample, ethylene glycol monomethyl ether, ethylene glycol monoethylether, ethylene glycol monobutyl ether, diethylene glycol monomethylether, and diethylene glycol monobutyl ether. Further,nitrogen-containing organic solvents, for example, nitrogen-containingorganic solvents, such as N-methyl-2-pyrrolidone, 1,3-dimethylimidazolidinone, monoethanolamine, N,N-dimethylethanolamine,N,N-diethylethanolamine, diethanolamine, N-n-butyldiethanolamine,triisopropanolamine, and triethanolamine may be as the organic solvent.

According to a preferred embodiment of the present invention, the inkcomposition used in the present invention further comprises awater-soluble polymer. Regarding the amount of the water-soluble polymeradded, the weight ratio of the water-soluble polymer to thethermoplastic resin is 1:10 to 1:1. Specific preferred examples of thewater-soluble polymer include polyalkyl oxides, such as polyethyleneoxide, polyvinyl pyrrolidone, polyvinyl alcohol, polyvinyl butyral,polyacrylic acid, glue, gelatin, casein, albumin, gum arabic, alginicacid, methyl cellulose, carboxylmethyl cellulose, hydroxy ethylcellulose, polyvinyl ether, polyvinyl methyl ether, and polyethyleneglycol.

According to a preferred embodiment of the present invention, the inkcomposition used in the present invention may further comprise asaccharide. Regarding the amount of the saccharide added, the weightratio of the saccharide to the thermoplastic resin in the inkcomposition is 1:5 to 1:1. Specific preferred examples of the saccharideinclude monosaccharides, disaccharides, polysaccharides, and glycosides,such as a-cyclodextrin, glucose, xylose, sucrose, maltose, arabinose,maltitol, and starch.

In order to improve various properties, suitable additives may be, ifnecessary, added to the ink composition used in the present invention.Specific examples of the additive include viscosity modifiers, surfacetension modifier, pH adjustors, multitudes, and preservatives. Morespecifically, at least one member selected from water-soluble anionic,cationic, amphoteric, and nonionic surfactants, which function toregulate the surface tension of the ink and to regulate the diameter ofthe dot on the recording paper may be added to the ink composition.Further, potassium dihydrogen phosphate, sodium dihydrogen phosphate,and the like may be added to as pH adjustor, and benzoic acid,dichlorophene, hexachlorophene, sorbic acid, p-hydroxybenzoic ester,ethylenediaminetetraacetic acid (EDTA), sodium dehydroacetate,1,2-benzothiazoline-3-one (trade name: Proxel XL II, manufactured byICI), 3,4-isothiazoline-3-one and the like may be added for mildewcide,preservative, rust prevention and other purposes. Furthermore, urea,thiourea, ethylene urea and the like may be added from the viewpoint ofpreventing the nozzle from drying.

According to a preferred embodiment of the present invention, thethermoplastic resin in the ink composition used in the present inventionis in the form of a resin emulsion. Further, when the ink compositioncontains a saccharide, it further contains a nonionic surfactant havinga polyoxyethylene group. The addition of the nonionic surfactant canimpart better water resistance, rubbing resistance, marker resistance,and water/rubbing resistance to prints.

The amount of the nonionic surfactant added is preferably 0.05 to 10% byweight based on the ink composition. When the nonionic surfactant ispresent in the ink composition, the weight ratio of the solid content ofthe resin emulsion to the saccharide in the ink composition ispreferably in the range of from 3:1 to 1:1.

According to a preferred embodiment of the present invention, a nonionicsurfactant having an HLB (hydro-lipophile balance) value of not lessthan 13 is preferred as the nonionic surfactant having a polyoxyethylenegroup.

Preferred examples of the nonionic surfactant having a polyoxyethylenegroup include acetylene glycol, alcohol ethylene oxide, polyoxyethylenealkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylenepolystilphenyl ether, polyoxyethylene polyoxypropylene glycol,polyoxyethylene polyol propylene alkyl ether, polyoxyethylene polyhydricalcohol fatty acid partial ester, polyoxyethylene fatty acid ester,polyglycerin fatty acid ester, polyoxyethylenated castor oil,polyoxyethylene alkylamine, and polyoxyethylene sorbitan fatty acidester. Among them, polyoxyethylene polyhydric alcohol fatty acid partialester and polyoxyethylene sorbitan fatty acid ester are preferred fromthe viewpoint of improving the light fastness.

Further, according to a preferred embodiment of the present invention,the ink composition used in the present invention contains an anionicsurfactant having a polyoxyethylene group when the thermoplastic resinis in the form of a resin emulsion. The addition of an anionicsurfactant can impart excellent ink ejection stability and resistance ofprints to rubbing and water.

The amount of the anionic surfactant added is preferably in the range offrom 0.001 to 0.5 in terms of the weight ratio wherein the solid contentof the resin emulsion is presumed to be 1. That is, the weight ratio ofthe solid content of the resin emulsion to the anionic surfactant in theink composition is preferably about 1000:1 to 2:1.

Preferred examples of anionic surfactant having a polyoxyethylene groupinclude polyoxyethylene alkyl ether sulfates, polyoxyethylenealkylphenyl ether sulfates, polyoxyethylene styrenated phenyl ethersulfates, polyoxyethylene alkyl ether phosphates, and polyoxyethylenealkyl phenyl ether phosphates. Particularly preferred arepolyoxyethylene alkyl ether sulfates and polyoxyethylene alkyl phenylether sulfates. Preferred examples of the salt include potassium,sodium, and ammonium salts and a salt with monoethanolamine,particularly a salt with ethanolamine. Among them, an ammonium salt isparticularly preferred. Further, according to a preferred embodiment ofthe present invention, the degree of polymerization of thepolyoxyethylene group is preferably about 3 to 10, and the alkyl grouppreferably has about 1 to 17 carbon atoms.

Furthermore, according to a preferred embodiment of the presentinvention, the ink composition used in the present invention contains anorganic acid when the thermoplastic resin is in the form of a resinemulsion. The addition of the organic acid can impart excellent rubbingresistance and water resistance to prints. The organic acid ispreferably an amino acid, its salt, or its derivative, and specificexamples thereof include L-ascorbic acid, D-iso-ascorbic acid(erythorbic acid), and glycine. The amount of the organic acid added ispreferably about 0.01 to 0.5% by weight based on the ink composition.

Various properties of the ink may be properly regulated. However,according to a preferred embodiment, the viscosity of the inkcomposition is preferably not more than 50 mPa.sec, still preferably notmore than 25 mPa.sec. The ink composition having the viscosity in theabove range can be stably projected through a printing head. Further,the surface tension of the ink composition may also be properlydetermined. In the case of multi-color printing, the surface tension ofa color ink composition is preferably 30 to 50 mN/m (25° C.).

Ink Jet Recording Apparatus

The ink jet recording apparatus according to the present invention willnow be described with reference to the accompanying drawings.

FIG. 7 shows an ink jet recording apparatus according to the presentinvention. In the drawing, platen 71 serves both as means for heating arecording medium and means for carrying the recording medium. Platen 71is a cylinder made of a metal having high thermal conductivity, forexample, aluminum, and is rotated in a direction indicated by an arrowby a drive (not shown). A silicone rubber or the like may be laminatedonto the surface of platen 71. Heater 72 is placed within platen 71 toheat platen 71. Further, paper pressing rollers 73 and 74 are in presscontact with platen 71, and recording medium 75 is interposed betweenplaten 71 and paper pressing rollers 73 and 74 the rotation of whichcarries recording medium 75. Paper pressing roller 73 comprises, forexample, a metallic core material and an acrylonitrile rubber bonded tothe surface of the core material. Paper pressing roller 74 may comprise,for example, a metallic core material and nylon fibers implanted in thecore material. Preferably, the rollers are rotated at a slightly higherspeed than platen 71. Ink jet printing head 76 is placed so as to faceplaten 71 with recording medium 75 sandwiched between ink jet printinghead 76 and platen 71. Printing head 76 may either one which forms inkdroplets by means of a piezoelectric element or one which forms inkdroplets by means of thermal energy. Preferably, printing head 76 may beprovided with, for example, 48 nozzles in any matrix form. The nozzlesof printing head 76 eject ink droplets based on printing data providedby an arithmetic unit (not shown). An ink composition is fed from inktank 77 into printing head 76, and printing head 76 can be moved in adirection orthogonal to the direction to which a recording medium iscarried by printing head drive 78.

Ink jet recording is carried out as follows. Recording medium 75 issandwiched between platen 71 and paper pressing rollers 73 and 74 and,in this state, carried. Recording medium 75 being carried comes intocontact with platen 71 heated by means of heater 72, whereby recordingmedium 75 is heated. Therefore, in an apparatus according to thisembodiment, the surface of platen 71 is preferably regulated so that thetemperature of recording medium 75 is brought to the softeningtemperature of the thermoplastic resin or above. Then, an ink droplet isselectively ejected onto carried recording medium 75 according to aprinting pattern by means of printing head 76. The ink droplet depositedon the recording medium is heated to form a film constituting an inkdot. Subsequently, the recording medium is carried by a predeterminedextent by means of platen 71 and paper pressing rollers 73 and 74, andrecording is again carried out by means of printing head 76. In thiscase, when ink dots are formed so as to adjoin each other or to be puton top of each other, it is preferred to carry out printing at certainprinting intervals. After necessary printing is carried out on recordingmedium 75, recording medium 75 is delivered from the apparatus.

FIG. 8 shows a recording apparatus according to another preferredembodiment of the present invention. In this apparatus, the sameelements as those in the apparatus shown in FIG. 7 have the samereference numerals as those in FIG. 7. This apparatus is provided withprinting heads separately for respective colors of ink compositions.Specifically, printing heads 81, 82, 83, and 84 respectively project ablack ink, a magenta ink, a cyan ink, and a yellow ink. These inks arefed from an ink tank 77 into the printing heads.

Printing with the apparatus shown in FIG. 8 is carried out basically thesame manner as described above in connection with printing using theapparatus shown in FIG. 7. Specifically, recording medium 75 is woundaround a platen 71 by means of a recording medium winding device 85.Then, printing in a single row or in a plurality of rows by means ofprinting heads 81 to 84 are carried out. Printing head 78 is then movedto a given extent, and printing is further carried out in a single rowor in a plurality of rows. The above procedure is repeated to record animage on recording medium 75.

Ejected ink compositions are color ink compositions, and in order toform a color image, different color ink compositions should be printedso as to adjoin each other or to be put on top of each other.Preferably, such printing is carried out while providing a certainperiod of time after the preceding printing.

Further, according to a preferred embodiment of the present invention,the ink jet recording apparatus of the present invention may comprise aplurality of printing heads and heating means respectively correspondingto the printing heads. FIG. 9 is a schematic enlarged diagram showingprinting heads and heating means of such an apparatus. This apparatuscomprises printing heads 91, 92, and 93 and platens 94, 95, and 96, eachwith a built-in heater, disposed so as to face the respective printingheads 91, 92, and 93. A recording medium is carried by means ofrecording medium carrying roller 97 and roller 98.

Recording is carried out by simultaneously or successively operating theplurality of printing heads. It should be noted that, when differentcolor ink compositions should be printed so as to adjoin each other orto be put on top of each other, printing is carried out at givenintervals with regulating the carrying speed of the recording medium.

Further, according to another embodiment of the present invention, therecording medium may be heated in a non-contact manner. Specifically, itmay be heated by applying a heat radiation to the recording medium or byblowing hot air against the recording medium. FIG. 10 shows an apparatuswherein recording medium 75 is heated by heating means 101 comprising anincandescent lamp and a reflector. FIG. 10 (A) shows an embodimentwherein after ink 102 is deposited onto a recording medium by means ofprinting head 76, ink 102 is heated by heating means 101. FIG. 10 (B)shows an embodiment wherein ink 102 is deposited by means of printinghead 76 onto recording medium 75 previously heated by heating means 101.

In the apparatus according to the present invention, the drivingfrequency and carriage speed of the printing head may be suitablydetermined. They, however, are preferably about 3 to 15 kHz and about100 to 1200 mm/sec, respectively.

EXAMPLES

The present invention will now be described in more detail withreference to the following examples, though it is not limited to theseexamples only.

In the following exmaples, "%" is by weight unless otherwise specified.

Example A

Ink compositions of Examples A1 to A18 specified in Table 1 wereprepared by a conventional method.

                                      TABLE 1                                     __________________________________________________________________________                      Example A                                                   Ingredient        1 2 3 4 5 6 7 8 9 10 11 12 13                                                                              14                                                                              15                                                                              16                                                                              17                                                                              18                     __________________________________________________________________________    Colorant                                                                      Carbon black      1.5                                                                             1.5                                                                             1.5                                                                             1.5                                                                             1.4                                                                             1.5                                                                             1.5                                                                             1.5                                                                             1.5                                                                             1.5                                                                              1.5                                                                              1.5                                                                              1.5                                                                             1.5                                                                             1.5                                                                             1.5                                                                             1.5                      C.I. Direct Black 154                                  1.5                    Thermoplastic resin                                                           Styrene/acrylic ester                                                                           3 5 15                                                                              23                                                                              40                                                                              45                                                                              12                                                                              12                                                                              12                                                                              12 12 15 15                                                                              15                                                                              15                           copolymer resin emulsion                                                      (softening point: 80° C.)                                              Styrene/methacrylic ester                          25                         copolymer resin emulsion                                                      (Tg: 82° C.)                                                           Polystyrene emulsion                                 25                       (m.p.: 720° C.)                                                        Styrene/acrylic ester copolymer                        15                     resin emulsion (MFT: 65° C.)                                           Others                                                                        Polyethylene oxide            16                                                                              12                                            Sodium alginate                   8 1.2                                                                              0.3                                    α-Cyclodextrin                      2  3 5                              Maltitol                                         10                           Sucrose                                            25                                                                              30                       Diethylene glycol 6 6 6 6 6 6 6 6 6 6  6  6  6   6 6 6 6                      Proportion of water-soluble polymer and                                                         0 0 0 0 0 0 4/3                                                                             1/1                                                                             2/3                                                                             1/10                                                                             1/15                                                                             2/15                                                                             1/5                                                                             1/3                                                                             2/3                                                                             1/1                                                                             5/5                                                                             0                      saccharide to thermoplastic resin                                             __________________________________________________________________________

The quality of prints formed using the ink compositions of Examples A1to A18 was evaluated as follows.

Evaluation A1

Feathering Length of Single-Color Ink

An ink jet printer having a fundamental construction shown in FIG. 7 wasused to carry out printing on XEROX-R paper (recycled paper,manufactured by XEROX Corp.), which had caused relatively large inkfeathering, among commercially available typical types of paper.

The length of ink feathering in a dot of the print was evaluatedaccording to the following criteria. Printing was carried out underconditions of a resolution of 300 dpi, an ink ejection frequency of 6kHz, a carriage travel speed of 1000 mm/sec, and a printing intervalbetween adjacent dots of at least 20 msec.

The heating temperature of the recording medium (platen temperature ofthe printer) was 120° C. The results were as given in Table 2. In theTable:

⊚⊚: Less than 1 μm (immeasurable)=No featuring occurred,

⊚: 1 to 3 μm=A good image could be formed on a recycled paper even in ahigh resolution exceeding 600 dpi,

∘: 3 to 5 μm=A good image could be formed on a recycled paper in aresolution of 360 to 600 dpi,

Δ: 5 to 10 μm=A good image could be formed on a recycled paper in aresolution up to 360 dpi, and

x: above 10 μm=An image quality was apparently deteriorated due to inkfeathering.

As a control, printing with the ink composition of Example A4 wascarried out in the same manner as described above, except that theheating temperature of the recording medium was 60° C. The inkfeathering of the print was evaluated according to the above criteria.The results are tabulated as Comparative Example A1 in Table 2.

                  TABLE 2                                                         ______________________________________                                        Example A                                                                           1      2     3     4   5     6   7     8   9                            ______________________________________                                        Results                                                                             ◯                                                                        ⊚                                                                    ⊚                                                                    ⊚                                                                  ⊚                                                                    ◯                                                                     ⊚                                                                    ⊚.circleincirc                                                 le. ⊚.circlein                                                     circle.                      ______________________________________                                                                    Compar-                                                                       ative                                                                         Example                                           Example A                   A                                                      10     11    12  13   14   15   16   17  18  1                           ______________________________________                                        Re-  ⊚⊚                                                     ⊚                                                                    ⊚                                                                  ⊚⊚                                                   ⊚⊚                                                   ⊚⊚                                                   ⊚⊚                                                   ⊚                                                                  ⊚                                                                  Δ                     sults                                                                         ______________________________________                                    

Evaluation A2

Ink Feathering in Multi-Color Printing

Solid printing (100% duty) of a yellow ink composition of Example A21was carried out on a recording paper XEROX 4024 (plain paper,manufactured by XEROX Corp.) using an ink jet printer having afundamental construction shown in FIG. 8, and a cyan ink composition ofExample A19 was printed thereon. Printing was carried out underconditions of a resolution of 600 dpi, an ink ejection frequency of 10kHz, a carriage travel speed of 400 mm/sec, and a printing intervalbetween yellow ink printing and magenta ink printing of 4 sec. Theheating temperature of the platen was 150° C.

The feathering length of a magenta ink in the resultant image was 1 toless than 3 μm, and a good color image could be provided even in aresolution exceeding 600 dpi.

On the other hand, printing was carried out in the same manner asdescribed above, except that the heating temperature of the platen was60° C. or room temperature. The resultant prints were investigated forfeathering. As a result, for all the prints, the feathering lengthexceeded 10 μm, and the images had a poor sharpness.

Evaluation A3

Ink Feathering in Multi-Color Printing

Solid printing (100% duty) of a yellow ink composition of Example A21was carried out on a recording paper XEROX 4024 (plain paper,manufactured by XEROX Corp.) using an ink jet printer having afundamental construction shown in FIG. 9, and a cyan ink composition ofExample A19 was printed thereon. Printing was carried out underconditions of a resolution of 600 dpi, an ink ejection frequency of 4kHz, a carriage travel speed of 200 mm/sec, and a printing intervalbetween yellow ink printing and magenta ink printing of 20 sec. Theheating temperature of the platen was 150° C.

The length of feathering of a magenta ink in the resultant image was 1to less than 3 μm, and a good color image could be provided even in aresolution exceeding 600 dpi.

Example B

Ink compositions of Examples B1 to B11, having compositions specified inTable 3, were prepared by a conventional method.

                                      TABLE 3                                     __________________________________________________________________________                           Example B                                              Ingredient             1  2  3  4  5  6  7  8  9 10 11                        __________________________________________________________________________    Colorant                                                                      Carbon black           1.5                                                                              1.5                                                                              1.5                                                                              1.5                                                                              1.5                                                                              1.6                                                                              1.5                                  C.I. Direct Black 154                       1.0                               C.I. Pigment Red 122                           1.3                            C.I. Pigment Blue 15                              1.3                         C.I. Pigment Yellow 1                                1.0                      Thermoplastic resin emulsion (solid content)                                  Styrene/acrylic ester copolymer                                                                      40 30 20 15 10 5  20 30                                Styrene/methacrylic ester copolymer            14                             Acrylic acid/acrylonitorile copolymer             14                          Alkyl ester of methacrylic acid/acrylic ester copolymer                                                                            14                       Saccharides                                                                   Maltitol               10 10    10    10    10 7  7  7                        Xylose                       10          10                                   Surfactant                         10                                         Nonionic                                                                      Polyoxyethylene sorbitan monolaurate                                                                 3        3           3                                 Polyoxyethylene sorbitan monostearate                                                                   3           3        3  3                           Polyoxyethylene octylphenyl ether                                                                          3           3           3                        Acetylene glycol alcohol ethylene oxide                                                                          3                                          High-boiling, volatile solvent                                                Diethylene glycol      6  6  6     3        6  3  3  3                        Ethylene glycol                 3  3                                          Glycerin                        3     6        2  2  2                        Ion-exchanged water    38.5                                                                             49.5                                                                             59.5                                                                             54.5                                                                             69.5                                                                             74.5                                                                             65.5                                                                             50 69.7                                                                             69.7                                                                             70                       Ratio of solid content of resin emulsion to saccharide                                               4:1                                                                              3:1                                                                              2:1                                                                              1.5:1                                                                            1:1                                                                              0.5:1                                                                            2:1                                                                              3:1                                                                              2:1                                                                              2:1                                                                              2:1                      __________________________________________________________________________

Evaluation B1

Feathering in Print

Printing was carried out in the same manner as in Evaluation A1, exceptthat ink compositions of Examples B1 to 11 were used. Feathering in theprints was evaluated in the same manner as in Example A1. The resultswere as given in Table 4.

                  TABLE 4                                                         ______________________________________                                               Example B                                                                       1      2        3    4      5    6                                   ______________________________________                                        Results  ⊚⊚                                                      ⊚⊚                                                       ⊚⊚                                                   ⊚⊚                                                     ⊚⊚                                                  ⊚                    ______________________________________                                                        Example B                                                                       7      8      9    10   11                                  ______________________________________                                                    Results                                                                             ⊚⊚                                                      ⊚⊚                                                     ⊚⊚                                                   ⊚⊚                                                   ⊚.circleincircle                                              .                                   ______________________________________                                    

Evaluation B2

Rubbing Resistance

Printing was carried out in the same manner as in Example B1, exceptthat the heating temperature of the platen was 100° C. and 120° C. Theresultant prints were evaluated for rubbing resistance as follows. Oneminute after printing, the prints were rubbed with a finger to observethe state of the prints. As a result, for all the prints heated at 100°C. and 120° C., no smearing was observed.

Evaluation B3

Water Resistance

Prints were obtained in the same manner as in Evaluation B2. After theywere completely dried, 1 cc of an aqueous alkali having pH 9 was droppedon the prints and the prints were spontaneously dried. Then, water wasdropped on the prints. As a result, no blurring was observed for all theprints heated at any temperature.

Evaluation B4

Water and Rubbing Resistance

Prints were obtained in the same manner as in Evaluation B2. Immediatelyafter printing, the prints were rubbed with Bemcot (manufactured byAsahi Chemical Industry Co, Ltd.) wetted with water at a pressure of 0.5g/mm² to evaluate the water-rubbing resistance of the prints. As aresult, rubbing with the Bemcot had no influence on the prints until theBemcot was moved forward and backward 7 times at the above pressure tocause the surface of the recording paper to be rubbed off.

Evaluation B5

Marker Resistance

Prints were obtained in the same manner as in Evaluation B1. Immediatelyafter printing, the prints were tested as follows. The prints were puton a cross-cut tester and further provided with an aqueous line marker.A load of 300 g was applied to the aqueous line marker, and the printswere rubbed with this loaded line marker. This did not cause anyunfavorable phenomenon, such as smearing, for all the prints heated atany temperature.

Evaluation B6

A black ink composition of Example B4 was printed alone in the samemanner as in Evaluation B2, except that the resolution, the platentemperature, and the printing frequency were changed to 720 dpi, 120°C., and 7.2 kHz, respectively. The size of the black ink dot was 65 μm.

In addition, solid printing (100% duty) of a yellow ink composition ofExample B11 was carried out under the above conditions, and a black inkcomposition of Example B4 was printed under the same conditions. Thesize of the black ink dot was 67 μm.

Evaluation B7

Solid printing of a yellow ink composition of Example B11 was carriedout in the same manner as in Evaluation B2, except that the resolution,the platen temperature, and the printing frequency were changed to 600dpi, 100° C., and 5 kHz, respectively. Further, solid printing of a cyanink composition of Example B10 was carried out so as to come intocontact with the yellow print area. Color-to-color bleeding in theinterface of two colors was about 1 to 5 μm.

Example C

Ink compositions of Examples C1 to C30, having compositions specified inTable 5, were prepared by a conventional method.

                                      TABLE 5                                     __________________________________________________________________________                                 Example C                                        Ingredient                   1  2  3  4  5  6  7  8  9   10 11                __________________________________________________________________________    Pigment                                                                       Carbon black                 1.5                                                                              1.5                                                                              1.5                                                                              1.5                                                                              1.5                                                                              1.5   1.5                                                                              1.5 1.5                                                                              1.5               C.I. Pigment Red 122                           1.5                            Anionic surfactant                                                            Polyoxyethylene alkyl ether ammonium sulfate                                                               3.0                                              Polyoxyethylene alkylphenyl ether ammonium sulfate                                                            3.0                                           Polyoxyethylene alkyl ether sodium sulfate                                                                       3.0               3.0                      Polyoxyethylene alkylphenyl ether sodium sulfate                                                                    3.0                                     Polyoxyethylene alkyl ether monoethanolamine sulfate                                                                   3.0             3.0                  Polyoxyethylene alkyl ether ammonium phosphate                                                                            3.0                               Polyoxyethylene alkyl ether potassium phosphate                                                                              3.0          3.0               Polyoxyethylene alkyl ether diethanolamine phosphate                                                                            3.0                         Thermoplastic resin emulsion                                                  Acrylic-emulsion (Primal-AC-61-manufactured by                                                             15.0                                                                             15.0     15.0                                                                             15.0         15.0                 Rohm & Haas)                                                                  Styrene acrylic resin emulsion (SG-60; manufactured by Gifu                                                      15.0lac     15.0  15.0   15.0              Manufacturing Co., Ltd. )                                                     Vinyl acetate resin emulsion (SC-802; manufactured by                                                               15.0        15.0                        Sony Chemical Corp.)                                                          Saccharides                                                                   Maltose                      10.0     10.0  10.0                                                                             10.0                           Ion-exchanged water          64.5                                                                             72.5                                                                             74.5                                                                             62.5                                                                             74.5                                                                             62.5                                                                             64.5                                                                             72.5                                                                             74.5                                                                              74.5                                                                             74.5              Glycerin                     6.0                                                                              6.0   6.0                                                                              6.0   6.0                                                                              6.0                                                                              6.0 6.0                                                                              6.0               Propylene glycol                   6.0      6.0                               Ethylene urea                   2.0   2.0   2.0   2.0                         Polyoxyethylene anionic surfactant/                                                                        1/5                                                                              1/5                                                                              1/5                                                                              1/5                                                                              1/5                                                                              1/5                                                                              1/5                                                                              1/5                                                                              1/5 1/5                                                                              1/5               thermoplastic resin emulsion ratio                                            __________________________________________________________________________                      Example C                                                   Ingredient        12  13   14  15   16 17  18 19  20 21  22 23                __________________________________________________________________________    Pigment                                                                       Carbon black      1.5 1.5  1.5 1.5  1.5                                                                              1.5 1.5                                                                              1.5 1.5                                                                              1.5 1.5                                                                              1.5               Anionic surfactant                                                            Polyoxyethylene alkyl ether ammonium                                                            0.005                                                                             0.0075                                                                             0.01                                                                              0.015                                                                              0.03                                                                             0.15                                                                              0.3                                                                              0.5 1.0                                                                              7.5 10.0                                                                             15.0              sulfate                                                                       Thermoplastic resin emulsion                                                  Acrylic emulsion (Primal AC-61;                                                                 15.0                                                                              15.0 15.0                                                                              15.0 15.0                                                                             15.0                                                                              15.0                                                                             15.0                                                                              15.0                                                                             15.0                                                                              15.0                                                                             15.0              manufactured by Rohm & Haas)                                                  Saccharides                                                                   Maltose           10.0                                                                              10.0 10.0                                                                              10.0 10.0                                                                             10.0                                                                              10.0                                                                             10.0                                                                              10.0                                                                             10.0                                                                              10.0                                                                             10.0              Ion-exchanged water                                                                             67.495                                                                            67.4925                                                                            67.49                                                                             67.485                                                                             69.47                                                                            67.35                                                                             67.2                                                                             67.0                                                                              66.5                                                                             60.0                                                                              57.5                                                                             52.5              Glycerin          6.0 6.0  6.0 6.0  6.0                                                                              6.0 6.0                                                                              6.0 6.0                                                                              6.0 6.0                                                                              6.0               Polyoxyethylene anionic surfactant/                                                             1/3000                                                                            1/2000                                                                             1/1500                                                                            1/1000                                                                             1/500                                                                            1/100                                                                             1/50                                                                             1/30                                                                              1/15                                                                             1/2 2/3                                                                              1/1               thermoplastic.sub.-- resin.sub.-- emulsion ratio                              __________________________________________________________________________                                   Example C                                      Ingredient                     24   25   26  27   28  29   30                 __________________________________________________________________________    Pigment                                                                       Carbon black                   1.5  1.5  1.5 1.5  1.5 1.5  1.5                Anionic surfactant                                                            Polyoxyethylene alkyl ether ammonium sulfate                                                                 1.5       1.5                                  Polyoxyethylene alkylphenyl ether ammonium sulfate                                                                         3.0  3.0 3.0  3.0                Polyoxyethylene alkyl ether sodium sulfate                                                                        1.5                                       Sodium dioctylsulfossucinate   1.5                                            Sodium alkylnaphthalenesulfonate    1.5                                       Sodium laurylsulfate                     1.5                                  Thermoplastic resin emulsion                                                  Styrene acrylic resin emulsion (SG-60; manufactured by Gifu                                                  15.0lac                                                                            15.0 150 14.0 11.0                                                                              9.0  7.5                Manufacturing Co., Ltd. )                                                     Water-soluble resin                                                           Polyvinyl alcohol: Denka Poval B-24; manufactured by                                                                       1.0  4.0 6.0  7.5                Denki Kagaku Kogyo k.k.                                                       Ion-exchanged water            80.5 80.5 80.5                                                                              74.5 74.5                                                                              74.5 74.5               Glycerin                                     6.0  6.0 6.0  6.0                Polyoxyethylene anionic surfactant/                                                                          1/10 1/10 1/10                                                                              1/4.7                                                                              3/11                                                                              1/3  1/2.5              thermoplastic resin emulsion ratio                                            __________________________________________________________________________

Evaluation C1

Feathering in Print

Printing was carried out in the same manner as in Evaluation A1, exceptthat ink compositions of Examples C1 to C30 were used. Feathering in theprints was evaluated in the same manner as in Example A1. The resultswere as given in Table 6.

                  TABLE 6                                                         ______________________________________                                        Example C                                                                     Results                                                                              1     2      3   4    5    6    7   8    9   10                        ______________________________________                                               ⊚⊚                                                    ⊚                                                                     ⊚                                                                  ⊚⊚                                                   ⊚                                                                   ⊚⊚                                                   ⊚⊚                                                  ⊚                                                                   ⊚                                                                  ⊚          ______________________________________                                        Example C                                                                     Results                                                                              11    12     13  14   15   16   17  18   19  20                        ______________________________________                                               ⊚                                                                    ⊚⊚                                                     ⊚⊚                                                  ⊚⊚                                                   ⊚⊚                                                   ⊚⊚                                                   ⊚⊚                                                  ⊚.circleincircle                                               .    ⊚.circleinc                                                    ircle.                                                                            ⊚.circl                                                        eincircle.                ______________________________________                                        Example C                                                                     Results                                                                              21    22     23  24   25   26   27  28   29  30                        ______________________________________                                               ⊚⊚                                                    ⊚⊚                                                     ⊚⊚                                                  ⊚                                                                   ⊚                                                                   ⊚                                                                   ⊚                                                                  ⊚.circleincircle                                               .    ⊚.circleinc                                                    ircle.                                                                            ⊚.circl                                                        eincircle.                ______________________________________                                    

Evaluation C2

Rubbing Resistance of Print

Prints were obtained and evaluated for rubbing resistance in the samemanner as in Example C1. That is, one min after printing, the printswere rubbed with a finger to investigate smearing in the printed area.The results were as given in Table 7. In the table:

∘: Strong rubbing with a finger resulted in smearing of the print,

Δ: Strong rubbing with a finger resulted in slight smearing of theprint, and

x: Even light rubbing with a finger resulted in smearing of the print.

Evaluation C3

Water Resistance of Print

Prints were obtained and evaluated for water resistance in the samemanner as in Example C1. That is, water droplets were dropped on theprints, and the prints were then observed. The results were as given inTable 7. In the table:

∘: No blurring occurred in the print,

Δ: Blurring occurred in edge of the print, and

X: The print was washed away with water.

The results were as given in Table 7 below.

Evaluation C4

Capability of Dry Ink to be Cleaned Up

Ink compositions of Examples C1 to C30 were dropped each in an amount of2 to 3 μg on a nozzle plate of a printing head of an ink jet printerMJ-500 (manufactured by Seiko Epson Corporation), and the ink jetprinter was then dried for 24 hr. Thereafter, cleaning operation of theprinter was carried out, and the state of the nozzle plate surface wasobserved under a microscope. The results were as given in Table 7. Inthe table:

⊚: The dry ink could be completely removed by single cleaning operation,

∘: Although the dry ink could not be completely removed by singlecleaning operation, this had no influence on ink ejection stability,

Δ: Although the dry ink could not be completely removed by repeatingcleaning operation twice, this had no influence on ink ejectionstability, and

X: The dry ink could not be completely removed even by repeatingcleaning operation thrice.

Evaluation C5

Ejection Stability

Prints were obtained in the same manner as in Evaluation C1. The printswere observed with the naked eye and under a microscope to evaluatescattering of dots (a phenomenon wherein fine ink droplets are scatteredaround a dot) and dropout. The results were as given in Table 7 below.In the table:

∘: Neither scattering of dots nor dropout was observed by visualinspection as well as by inspection under a microscope,

Δ: No droplet was observed although slight scattering of dots wasobserved by inspection under a microscope, and

X: Scattering of dots was so significant that the printed area was seendouble, and clear dropout was observed.

                                      TABLE 7                                     __________________________________________________________________________              Example C                                                           Evaluation test                                                                         1 2 3 4 5 6 7  8  9 10 11 12                                                                              13                                                                              14                                                                              15                                  __________________________________________________________________________    Evaluation C2:                                                                          ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                    ◯                                                                    ◯                                                                   ◯                                                                    ◯                                                                    ◯                                                                   ◯                                                                   ◯                                                                   ◯                       Rubbing resistance                                                            Evaluation C3:                                                                          ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                    ◯                                                                    ◯                                                                   ◯                                                                    ◯                                                                    ◯                                                                   ◯                                                                   ◯                                                                   ◯                       Water resistance                                                              Evaluation C4:                                                                          ⊚                                                                ⊚                                                                ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                   ◯-                                                                   ◯-                                                                   ◯                                                                   ◯-                                                                   ◯-                                                                   Δ                                                                         Δ                                                                         ◯                                                                   ⊚                    Capability of dry ink Δ                                                                          Δ                                                                            Δ                                                                          Δ                                      to be cleaned-up                                                              Evaluation C5:                                                                          ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                    ◯                                                                    ◯                                                                   ◯                                                                    ◯                                                                    ◯                                                                   ◯                                                                   ◯                                                                   ◯                       Ejection stability                                                            __________________________________________________________________________              Example C                                                           Evaluation test                                                                         16                                                                              17                                                                              18                                                                              19                                                                              20                                                                              21                                                                              22 23 24                                                                              25 26 27                                                                              28                                                                              29                                                                              30                                  __________________________________________________________________________    Evaluation C2:                                                                          ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                   Δ                                                                          Δ                                                                          ◯                                                                   ◯                                                                    ◯                                                                    ◯                                                                   ◯                                                                   ◯                                                                   ◯                       Rubbing resistance                                                            Evaluation C3:                                                                          ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                    ◯                                                                    ◯                                                                   ◯                                                                    ◯                                                                    Δ                                                                         Δ                                                                         Δ                                                                         Δ                             Water resistance                                                              Evaluation C4:                                                                          ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ◯                                                                    ◯                                                                    ◯                                                                   ◯                                                                    ⊚                                                                 ⊚                                                                ⊚                                                                ⊚                                                                ⊚                    Capability of dry ink                                                         to be cleaned-up                                                              Evaluation C5:                                                                          ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                   Δ                                                                          Δ                                                                          ◯                                                                   ◯                                                                    ◯                                                                    ◯                                                                   ◯                                                                   ◯                                                                   Δ                             Ejection stability                                                            __________________________________________________________________________

Example D

Ink compositions of Examples D1 to D14, for combinations of four colorsof black, cyan, magenta, and yellow, as specified in Table 8 wereprepared by a conventional method. In the table, either a colorant or adye were used.

                                      TABLE 8                                     __________________________________________________________________________                                 Example D                                        Ingredient                   1 2 3 4 5 6  7 8 9 10                                                                              11                                                                              12                                                                              13                                                                              14                    __________________________________________________________________________    Pigment                                                                           Carbon black             1.5                                                                             1.5                                                                             1.5      1.5                                                                             1.5                                                                             1.5                                                                             1.5                                                                             1.5                                                                             1.5                                                                             1.5                                                                             1.5                       C.I. Pigment Red 122     1.5                                                                             1.5                                                                             1.5      1.5                                                                             1.5                                                                             1.5                                                                             1.5                                                                             1.5                                                                             1.5                                                                             1.5                                                                             1.5                       C.I. Pigment Blue 15     1.3                                                                             1.3                                                                             1.3      1.3                                                                             1.3                                                                             1.3                                                                             1.3                                                                             1.3                                                                             1.3                                                                             1.3                                                                             1.3                       C.I. Pigment Yellow 1    1.3                                                                             1.3                                                                             1.3      1.3                                                                             1.3                                                                             1.3                                                                             1.3                                                                             1.3                                                                             1.3                                                                             1.3                                                                             1.3                   Dye C.I. Direct Black 154          0.5                                                                             0.5                                                                             0.5                                        C.I. Acid Yellow 23            0.9                                                                             0.9                                                                             0.9                                        C.I. Direct Red 92             0.8                                                                             0.8                                                                             0.8                                        C.I. Direct Blue 88            0.8                                                                             0.8                                                                             0.8                                    Thermoplastic resin                                                           Styrene/acrylic ester copolymer                                                                            3 5 15                                                                              23                                                                              45                                       resin emulsion (MFT: 82° C.)                                           Styrene/methacrylic ester              15 5 10                                                                              5   10                                                                              15                                                                              15                                                                              15                    copolymer resin emulsion (Tg: 75° C.)                                  Polyethylene emulsion (m.p.: 72° C.)     18                            Polyethylene oxide                          10                                                                              6                               Sodium alginate                        0.5                                                                              3                                   α-Cyclodextrin                          3                               Maltitol                                            10                                                                              15                      Sucrose                                           25    30                    Nonionic surfactant:                          3     1                         Polyethylene nonylphenyl ether                                                Anionic surfactant:                                                           Sodium dialkylsulfossucinate     0.5                                                                             0.5                                                                             1    1.5                                                                             0.5   0.5   0.5                   Ethanol                      3                          3                     Propylene glycol               6 6                                            Diethylene glycol            6              6 6   6 6 6                       Glycerin                           6 6    6             6                     Water-soluble polymer or saccharides/solid content of resin                                                          1/30sion                                                                         3/5                                                                             1/1                                                                             6/5                                                                             1/6                                                                             5/2                                                                             2/3                                                                             1/1                                                                             2/1                   Surface tension (mN/m: 20° C.)                                                                      42                                                                              40                                                                              40                                                                              42                                                                              30                                                                              46 33                                                                              38                                                                              35                                                                              43                                                                              33                                                                              36                                                                              48                                                                              35                    __________________________________________________________________________

Evaluation D1

Feathering in Print

Printing was carried out in the same manner as in Evaluation A1, exceptthat ink compositions of Examples D1 to D14, for four colors of black,cyan, magenta, and yellow, were used. Feathering in the prints wasevaluated in the same manner as in Example A1. The results were as givenin Table 9.

                  TABLE 9                                                         ______________________________________                                        Example D                                                                             1       2     3      4   5     6   7                                  ______________________________________                                        Results ◯                                                                         ⊚                                                                    ⊚                                                                     ⊚                                                                  ◯                                                                       ⊚                                                                  ⊚.circleincircle                                               .                                  ______________________________________                                        Example D                                                                             8       9     10    11  12     13   14                                ______________________________________                                        Results ⊚⊚                                                      ⊚                                                                     ⊚                                                                    ⊚                                                                  ⊚⊚                                                    ⊚⊚                                                    ⊚                 ______________________________________                                    

Evaluation D2

Variation in Dot Diameter and Deviation in Color

Recording papers were a) a recycled paper which, among commerciallyavailable recording papers, is likely to generally cause relativelylarge ink feathering and b) a copying paper which is likely to causemedium ink feathering, and c) a special paper, for ink jet recording,which is less likely to cause feathering.

I) Black ink compositions were printed alone on these papers in the samemanner as in Evaluation D1. The difference in dot diameter amongrecording papers was evaluated according to the following criteria.

⊚: Difference of not more than 25%

∘: Difference of not more than 30%

X: Difference exceeding 30%

II) Six colors in total of yellow, cyan, and magenta inks and colorsformed by putting these colors on top of each other, i.e., red, green,and blue, were printed in the same manner as in Evaluation D2. Thedeviation in dots, i.e., deviation in color, was evaluated by visualinspection according to the following criteria.

⊚: Deviation in color was observed.

∘: Deviation in color was observed in such an extent that the wholeimage is not deteriorated.

X: Deviation in color deteriorated the whole image.

Evaluation D3

Variation in Dot Diameter in Overlapping of Colors

Diameters of three dots, i.e., a) a diameter of a dot of a cyan inkcomposition printed alone on a recording paper, b) a diameter of a cyandot formed by carrying out solid printing (100% duty) of a yellow inkcomposition on a recording paper, and c) a diameter of a cyan dot formedby carrying out solid printing (100% duty) of a yellow ink compositionon a recording paper, carrying out solid printing a magenta inkcomposition thereon, and further printing a cyan ink composition thereonwere compared with one another. The difference in diameter of the threedots was evaluated according to the following criteria.

⊚: Difference of not more than 25%

∘: Difference of not more than 30%

X: Difference exceeding 30%

The results were as given in Table 10.

                                      TABLE 10                                    __________________________________________________________________________             Example D                                                                     1 2 3 4 5 6 7 8 9 10                                                                              11                                                                              12                                                                              13                                                                              14                                         __________________________________________________________________________    Evaluation D2.I.                                                                       ◯                                                                   ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                           Evaluation D2.II.                                                                      ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                   ⊚                                                                ⊚                                                                ◯                                                                   ◯                                                                   ⊚                                                                ⊚                                                                ⊚                                                                ◯                              Evaluation D3                                                                          ◯                                                                   ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                           __________________________________________________________________________

Example E

Ink compositions of Examples E1 to E9, having compositions specified inTable 11, were prepared by a conventional method.

                                      TABLE 11                                    __________________________________________________________________________                           Example E                                              Ingredient             1  2  3  4  5  6  7   8  9                             __________________________________________________________________________    Colorant                                                                      Carbon black           1.5                                                                              1.5                                                                              3.0                                                                              3.0                                                                              5.0                                                                              5.0                                     C.I. Pigment Blue 15                     3.0                                  C.I. Pigment Red 122                         3.0                              C.I. Pigment Yellow 1                           3.0                           C.I. Direct Black 19                                                          Thermoplastic resin                                                           Styrene/acrylic resin  10.0                                                                             10.0                                                Three dimensionally crosslinked styrene/acrylic resin                                                      15.0                                                                             15.0     15.0                                                                              15.0                                                                             15.0                          emulsion                                                                      Acrylic resin emulsion             10.0                                       Vinyl acetate resin emulsion          15.0                                    Organic acid                                                                  L-Ascorbic acid        0.01           0.005                                   Sodium L-ascorbate        0.1      0.15  0.6                                  Erythorbic acid              0.05                                             Sodium erythorbate              0.1                                           Glycine                      0.05            0.3                              Disodium ethylene diaminetetraacetate        0.3                              Calcium disodium ethylene diaminetetraacetate   0.001                         Styrene/acrylic copolymer (dispersant)                                                               0.3                                                                              0.3                                                                              0.6                                                                              0.6                                                                              1.0                                                                              1.0                                                                              0.6 0.6                                                                              0.6                           Triethanolamine (counter ion)                                                                        0.12                                                                             0.12                                                                             0.24                                                                             0.24                                                                             0.4                                                                              0.4                                                                              0.24                                                                              0.24                                                                             0.24                          Saccharose             10.0           10.0                                                                             10.0                                                                              10.0                                                                             10.0                          Maltitol                           20.0                                       Diethylene glycol      6.0                                                                              6.0            5.0 5.0                                                                              5.0                           Dipropylene glycol           6.0                                                                              5.0                                           Glycerin                           5.0                                                                              5.0                                     Ethanol                1.0      1.0                                           Ion-exchanged water    71.07                                                                            81.53                                                                            75.06                                                                            75.06                                                                            75.06                                                                            58.45                                                                            63.595                                                                            65.56                                                                            66.159                        __________________________________________________________________________

Evaluation E1

Feathering in Print

Printing was carried out in the same manner as in Evaluation A1, exceptthat ink compositions of Examples E1 to E9 were used. Feathering in theprints was evaluated in the same manner as in Example A1. The resultswere as given in Table 12.

                  TABLE 12                                                        ______________________________________                                        Example E                                                                     1        2     3       4   5     6   7     8   9                              ______________________________________                                        Results                                                                             ⊚⊚                                                     ⊚                                                                    ⊚                                                                    ⊚                                                                  ⊚                                                                    ⊚⊚                                                  ⊚⊚                                                    ⊚                                                                  ⊚.circlein                                                     circle.                      ______________________________________                                    

Evaluation E2

Storage Stability

Ink compositions were placed in a hermetically sealed state in anenvironment of 60° C. for one month. They were then evaluated for pHchange, the occurrence of precipitates, and the viscosity changeaccording to the following criteria. pH change:

⊚: No change from the initial value observed.

∘: A change of not more than 5% from the initial value was observed.

X: A change of more than 5% from the initial value was observed.Occurrence of precipitates:

⊚: No precipitate was formed.

∘: Although precipitates were formed, it disappeared upon stirring.

X: Precipitates were formed and did not disappear even after stirring.Viscosity change:

⊚: No change from the initial value observed.

∘: A change of not more than 5% from the initial value was observed.

X: A change of more than 5% from the initial value was observed.

Evaluation E3

Rubbing Resistance and Water Resistance

The rubbing resistance and the water resistance were evaluated in thesame manner as in Evaluation C2 and Evaluation C3.

The results were as given in Table 13.

                  TABLE 13                                                        ______________________________________                                                  Example E                                                           Evaluation test                                                                           1      2     3   4   5    6   7   8   9                           ______________________________________                                        E2  pH change   ⊚                                                                     ⊚                                                                  ◯                                                                     ◯                                                                     ⊚                                                                   ◯                                                                     ⊚                                                                  ⊚                                                                  ◯                 Precipitate ⊚                                                                     ⊚                                                                  ⊚                                                                  ⊚                                                                  ⊚                                                                   ◯                                                                     ◯                                                                     ⊚                                                                  ⊚              Viscosity change                                                                          ⊚                                                                     ⊚                                                                  ⊚                                                                  ⊚                                                                  ◯                                                                      ⊚                                                                  ◯                                                                     ◯                                                                     ◯             E3  Water resistance                                                                          ⊚                                                                     ⊚                                                                  ⊚                                                                  ⊚                                                                  ⊚                                                                   ⊚                                                                  ⊚                                                                  ◯                                                                     ⊚              Rubbing     ⊚                                                                     ⊚                                                                  ⊚                                                                  ⊚                                                                  ⊚                                                                   ⊚                                                                  ⊚                                                                  ⊚                                                                  ⊚              resistance                                                                ______________________________________                                    

Example F

Ink compositions of Examples F1 to F6, having compositions specified inTable 14, were prepared by a conventional method.

                                      TABLE 14                                    __________________________________________________________________________                           Example F                                              Ingredient             1   2   3   4   5       6                              __________________________________________________________________________    Colorant                                                                      Carbon black           1.5 1.5 1.5                                            C.I. Pigment Blue 15               1.5                                        C.I. Acid Yellow 23                    1.5                                    C.I. Direct Red 92                             1.5                            Thermoplastic resin emulsion                                                  Styrene/acrylic ester resin emulsion (MFT: 82° C.)                                            15.0                                                                              15.0                                                                              15.0                                                                              15.0                                                                              15.0    15.0                           Maltitol               10.0                                                                              10.0                                                                              7.0 7.0 7.0     7.0                            Sodium L-ascorbate     0.03                                                                              0.03                                                                              0.03                                                                              0.03                                                                              0.03    0.03                           Disodium ethylene diaminetetraacetate                                                                    0.03                                               Nonionic surfactant:                                                          Acethylene glycol alcohol ethylene oxide                                                                 0.2 0.1 0.1 0.1                                    Anionic surfactant:                                                           Polyoxyethylene alkylphenyl ether ammonium sulfate                                                   0.3     0.3 0.3 0.3     0.3                            Diethylene glycol      3.0 3.0 12.0                                                                              12.0                                                                              12.0    12.0                           Water                  Balance                                                                           Balance                                                                           Balance                                                                           Balance                                                                           Balance Balance                        __________________________________________________________________________

Evaluation F1

Feathering in Print

Printing was carried out in the same manner as in Evaluation A1, exceptthat ink compositions of Examples F1 to F6 were used. Feathering in theprints was evaluated in the same manner as in Example A1. The resultswere as given in Table 15.

                  TABLE 15                                                        ______________________________________                                               Example F                                                                     1   2         3     4       5   6                                      ______________________________________                                        Results  ⊚⊚                                                    ⊚⊚                                                        ⊚⊚                                                  ⊚⊚                                                      ⊚⊚                                                  ⊚⊚     ______________________________________                                    

Evaluation F2

Ejection Stability

Prints were obtained in the same manner as in Evaluation F1 and wereevaluated in the same manner as in Evaluation C5.

Evaluation F3

Rubbing Resistance of Print

Prints were obtained in the same manner as in Evaluation F1 and wereevaluated for the rubbing resistance in the same manner as in EvaluationC2.

Evaluation F4

Water Resistance of Print

Prints were obtained in the same manner as in Evaluation F1 and wereevaluated for the water resistance in the same manner as in EvaluationC3.

Evaluation F5

Capability of Dry Ink to be Cleaned Up

For the ink compositions of Examples F1 to F6, the capability of dry inkto be cleaned up was evaluated in the same manner as in Evaluation C4.

Evaluation F6

Storage Stability

The ink compositions of Examples F1 to F6 were evaluated for the storagestability in the same manner as in Evaluation E2.

The results of Evaluations F2 to F6 were as given in Table 16.

                  TABLE 16                                                        ______________________________________                                                   Example F                                                          Evaluation   1     2        3   4     5   6                                   ______________________________________                                        F2           ◯                                                                       ◯                                                                          ◯                                                                     ◯                                                                       ◯                                                                     ◯                       F3           ◯                                                                       ◯                                                                          ◯                                                                     ◯                                                                       ◯                                                                     ◯                       F4           ◯                                                                       ◯                                                                          ◯                                                                     ◯                                                                       ◯                                                                     ◯                       F5           ⊚                                                                    ⊚                                                                       ⊚                                                                  ⊚                                                                    ⊚                                                                  ⊚                    F6                                                                            pH change    ⊚                                                                    ⊚                                                                       ⊚                                                                  ⊚                                                                    ⊚                                                                  ⊚                    Precipitate  ⊚                                                                    ⊚                                                                       ⊚                                                                  ⊚                                                                    ⊚                                                                  ⊚                    Viscosity change                                                                           ⊚                                                                    ⊚                                                                       ⊚                                                                  ⊚                                                                    ⊚                                                                  ⊚                    ______________________________________                                    

We claim:
 1. An ink jet recording method comprising the steps of:(a)providing at least one ink composition comprising a colorant, athermoplastic resin and water, said thermoplastic resin having atemperature at which the thermoplastic resin softens when heated; (b)ejecting a plurality of droplets of the at least one ink compositiononto the recording medium to deposit on the recording medium a pluralityof ink dots that are spaced apart whereby the deposited dots have aresolution which is a reciprocal of a pitch of the dots; and (c) heatingthe recording medium with the deposited dots at the softeningtemperature of the thermoplastic resin or higher so as effectively toinhibit feathering of the ink composition, said heating being controlledsuch that the feathering, as measured by a length that an outermostportion of a deposited droplet extends from a circle of maximum sizeinscribable in the deposited droplet, does not exceed about 10% of avalue obtained by multiplying the pitch by 1.5 √2/2, said heatingresulting in formation of at least a first print on the recordingmedium.
 2. The method according to claim 1, wherein the resolution isnot less than 600 dpi and, in the step of heating, the recording mediumis heated so that the feathering is not more than 5 μm.
 3. The methodaccording to claim 1, wherein the ink composition comprises 5 to 40% byweight of the thermoplastic resin.
 4. The method according to claim 1,wherein the thermoplastic resin is present in the form of a resinemulsion in the ink composition.
 5. The method according to claim 1,wherein the ink composition further comprises a water-soluble polymer.6. The method according to claim 5, wherein the amount of thewater-soluble polymer in the ink composition is such that thewater-soluble polymer to thermoplastic resin weight ratio is 1:10 to1:1.
 7. The method according to claim 1, wherein the ink compositionfurther comprises a saccharide.
 8. The method according to claim 7,wherein the amount of the saccharide in the ink composition is such thatthe saccharide to thermoplastic resin weight ratio is 1:5 to 1:1.
 9. Themethod according to claim 3, wherein the ink composition furthercomprises a nonionic surfactant having a polyoxyethylene group.
 10. Themethod according to claim 8, wherein the amount of the nonionicsurfactant in the ink composition is 0.05 to 10% by weight based on theink composition.
 11. The method according to claim 9, wherein the ratioof a solid content of the resin emulsion to the saccharide in the inkcomposition is 3:1 to 1:1.
 12. The method according to claim 3, whereinthe ink composition further comprises an anionic surfactant having apolyoxyethylene group.
 13. The method according to claim 12, wherein theratio of a solid content of the resin emulsion to the anionic surfactantin the ink composition is 1000:1 to 2:1.
 14. The method according toclaim 3, wherein the ink composition further comprises an organic acid.15. The method according to claim 14, wherein the organic acid is anamino acid, its salt, or its derivative.
 16. The method according toclaim 15, wherein the amount of the amino acid, its salt, or itsderivative in the ink composition is 0.01 to 0.5% by weight based on theink composition.
 17. The method according to claim 1, wherein therecording medium comprises means for fixation of an ink composition. 18.The method according to claim 1, wherein the recording medium has fibersinto which the ink composition penetrates to form an ink dot.
 19. Themethod according to claim 18, wherein the recording medium is arecording paper.
 20. The method according to claim 1 comprisingproviding a second ink composition comprising a second colorant, asecond thermoplastic resin and water, and ejecting a plurality ofdroplets of the second ink composition onto or adjacent the first printafter step (c), the heating in step (c) being controlled such that theejection of the second ink composition forms a second print that doesnot bleed with the first print.
 21. The method according to claim 1,wherein said heating in step (c) is controlled such that the featheringdoes not exceed about 10% of a value obtained by multiplying the pitchby √2/2.